It is a well known practice within Dye Diffusion Thermal Transfer printers that, in order to controllably drive the paper and maintain image registration between color passes, an aggressively textured drive roller, and a companion pinch roller that applies a load between the paper and drive roller, is commonly used. This type of drive system does not result in any image artifacts on the printed paper when printing only on one side, or simplex printing, because the aggressively textured drive roller is not contacting the printed side of the paper. This method does present a problem when printing a two-sided, or duplex print because the aggressively textured drive roller must contact both sides of the printed sheet. For two-sided or duplex printing, the paper surface that is in contact with the aggressively textured surface of the drive roller may become compromised by the aggressively textured surface. This compromised paper surface may not receive dye transfer as readily, resulting in a visible density difference between the area of the paper that saw contact with the drive roller's aggressive texture and the area that did not contact the aggressive texture.
It is also common practice within the Dye Diffusion Thermal Transfer printer firmware to incorporate compensation algorithms that correct for across the page density variations, and/or down the page density variations. There may be limitations within the printer hardware or printer firmware such that compensation algorithms cannot completely compensate for printing artifacts generated by the drive roller. Due to these limitations, it becomes important to minimize the number of times that new contact occurs between the aggressively textured drive roller and the paper surface.
With respect to FIGS. 2-3, for two-sided or duplex Dye Diffusion Thermal Transfer printing, one common method is to use two thermal print heads 117, 137, as shown in FIG. 2, drive the rolled print paper 110 via drive roller (or feed roller) 113 and pinch roller 112 to between platen roller 123 and one thermal print head 117 (hereinafter TPH1), print on one side of the print paper 100, then re-position the paper by reversing feed roller 113 and, as shown in FIG. 3, drive the print paper via drive roller 113 and pinch roller 141 to between platen roller 131 and the second thermal print head 137 (hereinafter TPH2), and print on the non-printed surface 101 of the print paper. Sensors 124 and 130 detect paper position in the printer. After completion of printing on both surfaces 100, 101 of the print paper, the printed paper is ejected from the printer along paths 121 or 133, and is commonly collected via exit guide 125, after being cut by cutters 126 and output via rollers 127 into a paper catch tray 128.
With reference to FIG. 4, there is illustrated a length of paper driven through the drive roller 113 and pinch roller 141, exposing paper surface 100 to come into contact with the drive roller's aggressive surface texture, compromising the paper surface 100 for subsequent prints. In a non-preferred printing method which one might normally expect if given the above sequence of printing steps, the next two-sided print job would again be staged to print using thermal print head TPH1 on paper side 100 (see FIG. 7), and then re-position the paper, and drive the paper to the other thermal print head TPH2 and print on the non-printed side of the print paper 101, thus repeating the steps of FIGS. 2, 3 and 4. This printing sequence introduces an unnecessary repositioning of the paper between TPH2 137 and side 101 of the paper back over to TPH1 117 and side 100 of the paper, once again unnecessarily exposing the paper surfaces to come into contact with the drive roller's aggressive surface texture during the retraction, compromising the paper surfaces.
With regard to photobook printing, a known method to generate the sequential page content and sending the image data to the printer so that a photo book is printed with proper page order is illustrated in FIG. 8 wherein a host computer 10 communicates a host request to a connected printer 50 and receives a printer response. This is a common method of a host computer communicating with the connected printer, typically through USB connection, wired ethernet, or wireless connection. FIG. 9 shows a typical print job printing page sequence sent from the Host Computer to the Printer: Page 10 951, Page 9 950, Page 8 941 , Page 7 940, Page 6 931 , Page 5 930, Page 4 921, Page 3 920, Page 2 911, Page 1 910. The pages are sent to the printer in reverse sequential order so that the last printed page that is ejected in to the print catcher tray 128 is the first page of the photo book. An alternate typical Print Job Printing Sequence (reversed) would be: Page 1, Page 2, Page 3, Page 4, Page 5, Page 6, Page 7, Page 8, Page 9, Page 10. This page order would result in the photo book being face-down in the print catcher tray, but would still be in proper page order.